The present invention relates to articles molded from flake-wood particles, such as pallets for use in material handling, and having at least one non-planar portion displaced from a major plane and, more particularly, to methods for making such articles.
Considerable effort has been devoted to developing techniques for molding articles including non-planar portions from an inexpensive residue and surplus woods. One area of particular interest for utilizing such woods is in the production of material handling pallets.
In one method of molding such pallets, a loosely-felted mat formed from a mixture of flake-like wood particles and a binder or so-called furnish is deposited on the lower or female die of a pallet-forming mold including a plurality of cavities which form the legs for the pallet. The upper or male die of the mold extrudes the wood particles downwardly into the leg-forming cavities during compression of the mat. Such a method is disclosed in U.S. Caughey et al Pat. No. 4,248,163, U.S. Haataja et al Pat. No. 4,408,544 and U.S. Haataja et al Pat. No. 4,440,708.
When the legs are longer and/or intricately designed, the mat material may be pulled apart to form voids which can cause localized weak spots as well as rough spots in the surface which affects the appearance of the pallet. FIGS. 5-7 of U.S. Haataja et al Pat. No. 4,440,708 illustrate different techniques for alleviating this difficulty. In one technique, the leg-forming cavities in the female die are substantially filled with furnish and a loosely-felted mat formed outside the mold is deposited on the female die over the filled cavities prior to closing the mold. In another technique, a loosely-felted mat is formed outside the mold and mounds of furnish are deposited on top of the mat at the locations corresponding to the female die cavities prior to placing the mat in the mold. In another technique, a mat is loosely felted directly onto the female mold and the cavities are filled with furnish during mat formation.
U.S. Sandberg et al Pat. No. 4,790,966 discloses still another technique in which the leg-forming cavities in the female die are filled with furnish and a two-layer, loosely-felted mat is deposited thereover. The wood particles in both layers of the mat are generally parallel aligned and those in one layer extend transversely to those in the other layer. This patent also discloses the use of a separate caul sheet which has a shape corresponding to the female die and is supported by the female die during formation of the pallet. The furnish and double-layered mat is deposited on the caul sheet and the caul sheet is inserted into the female die for a molding.
These prior methods for forming relatively long or intricately designed legs involve either several expensive processing steps and/or a separate caul sheet including leg-forming cavities which is quite expensive to fabricate.